A rail vehicle “consist” is a group of two or more rail vehicles that are mechanically coupled or linked together to travel along a route, as defined by a set of rails that support and guide the rail vehicle consist. One type of rail vehicle consist is a train, which may include one or more locomotives (or other powered rail cars) and one or more non-powered rail cars. (In the context of a rail vehicle consist, “powered” means capable of self propulsion and “non-powered” means incapable of self propulsion.) Each locomotive includes traction equipment for moving the train, whereas each rail car is configured for hauling passengers or freight. For producing motive effort, most modern locomotives use electric motors. In a typical case, a locomotive will include plural motors. For each motor, a pinion gear is attached to the output shaft of the motor, for driving a bull gear operably attached to a traction wheel set of the locomotive. For operation of the motor, the motor is supplied with electricity. In some locomotives, the locomotive may include an on-board power source for providing traction electricity (meaning electricity of suitable magnitude to power traction motors for moving a train). In other locomotives, traction electricity is received from an off-board source, such as a third rail or an overhead catenary line.
In a train or other rail vehicle consist, it may be desirable to communicate data from one rail vehicle in the consist to another rail vehicle in the consist. Such data may be used for control purposes, such as braking control or distributed power operations. (Distributed power refers to the coordinated control of plural locomotives or other powered rail vehicles which may be separated by unpowered vehicles and distributed throughout the rail vehicle consist.) Data may be communicated wirelessly (e.g., via radio waves), or over electrical lines that are at least partially disposed within the rail vehicles and extend between the rail vehicles in the consist. However, the former wireless communication is expensive to implement, and there may be signal quality issues due to RF interference and the like. The latter electrical line communication may provide a secure and noise-free communication channel, but it may not be possible to outfit a rail vehicle consist with an electrical line that extends along the entirety of the length of the consist. For example, many non-powered rail cars such as freight cars) do not include “built in” communication lines, and outfitting cars with such lines is expensive and impractical (that is, the cars are not designed to accept “add-on” communication lines). Further, even if all the rail vehicles in a rail vehicle consist are interconnected with a cable or other communication line, such lines may be subject to failure (e.g., detachable lines between adjacent cars becoming disconnected due to vibration).